## Art with power spectrum estimation

Above is a estimation of power spectrum for a large number of very
closely spaced concentric circles (see equation below). A two dimensional Welch method was
used to estimate the spectrum. Aliasing is the source of this neat
effect. Note that fftshift has not been performed so that zero frequency
is represented on the four corners of this plot. I
used the same power spectra estimation algorithm I use for
my research.

Above you see the actual signal plotted. Notice that it doesn't look very much like concentric circles at all (although the equation below states that it should). This is because the distance between pixels is smaller than the distance between the circles so makes kind of its own aliasing-like effect.

signal=sin(((20*x*)^2+(20*y*)^2)^4/10)